The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art
Powertrain systems including hybrid powertrain systems, electric-only powertrain systems, and extended-range electric powertrain systems are configured to operate in a plurality of operating modes. Such powertrain systems use torque generators, clutches and transmissions to transfer torque to a driveline. Executing a shift from a first operating mode to a second operating mode may include executing a direct shift process that includes deactivating an off-going clutch and activating an oncoming clutch. Propulsion torque during shift execution may be maintained by slipping either an oncoming clutch or an off-going clutch while synchronizing speeds of clutch elements of the oncoming clutch before fully applying the oncoming clutch, with an applied clutch that is common for the first and second states being continuously applied during the shift execution. Synchronizing the speeds of the clutch elements includes controlling operation of one of the torque generators to achieve a synchronization speed. Other powertrain control permutations to maintain output torque during a shift execution are known.
Known issues associated with executing a direct shift process include driveline power loss and energy loss during clutch slippage. The power loss during clutch slippage may be discernible by a vehicle operator.